turn your back on someone
turn (one's) back on (someone or something)
To ignore, disregard, or exclude someone or something; to abandon, give up on, or forsake someone or something. It's clear that the company has turned its back on customers. After becoming a successful writer, Jim turned his back on all the people he used to know back home.
turn your back on someone
COMMON If someone turns their back on you, they ignore you and refuse to help you. We appeal to this conference — do not turn your back on the poor. Our job is to protect children and we can't just turn our backs on them.